[Hematopoietic organs in mice following a single administration of hydrocortisone]

Kinetics of the number and direction of CFU differentiating in mice after a single infusion of hydrocortisone in a dose of 5 mg per mouse was studied using the method of an exogenous cloning of the stem cells in the spleen and the bone marrow of the irradiated recipients. Against the background of the long-term involution of the thymicolymphoid apparatus a change of the number and direction of the CFU differentiating occurred. Along with this, CFU concentration in the spleen and bone marrow of mice remained constant. Under the hormone action CFU differentiating capacity in the spleen and bone marrow in the direction of erythro- and myelopoiesis sharply changes; CFU of the bone marrow behaves as CFU of the spleen, and CFU of the spleen behaves as CFU of the bone marrow of normal mice. It is suggested that the described effects of the CFU of the spleen and bone marrow of mice given hydrocortisone were due to the redistribution of T-lymphocytes and not to direct cytotoxic effect of hydrocortisone on the CFU population.